1. Field of the Invention
This invention relates generally to the internal mounting mechanism of an electronic system, e.g., a portable computer, and more particularly, to an electronic system comprising one or more electronic module assemplies with external I/O ports and an external enclosure case for mounting all these modules.
2. Description of the Prior Art
The internal I/O module design for portable computers such as notebook or palmtop computers has been an area in which progress has not kept up with the fast growing personal computer industry. There is no industry standard for internal I/O modules such as internal modems or LAN adapters. Most portable manufacturers still use their own proprietary modular solutions to differentiate themselves from others. Since there is no internal I/O module standard for peripheral vendors to follow, three different electronic packaging methods have been used by peripheral vendors to overcome this problem.
The first packaging method is by means of external portable modules. Many compact and light-weight portable modules have been developed and produced by peripheral vendors using this first alternative. Users may select a variety of portable modules from many vendors offering external module solutions. However, portable modules have some serious weaknesses when compared with internal modules. First, external modules usually require alternative, external power sources. Second, the user has to set up the module whenever he/she wants to use the portable module's feature, and he/she must pack it up after finishing with it. And finally, the external interface speed is necessarily slow, making the external module impractical given the power and speed provided by the state-of-the-art CPUs running in most portable computers.
The second packaging method is customized integration by convincing portable computer vendors to integrate needed I/O modules such as Ethernet adapter into their portable computer motherboards. Such integration may ultimately reduce the packaging cost and also provide very good performance, but it also raises some questions. First of all, the existing hard tooling often must be modified to include the integrated I/O port. Secondly, it is difficult to provide flexibility and alternative solutions within such integrated designs. Any variation or modification becomes a new design. Thirdly, customers who have no need for the integrated feature are forced to pay for it.
The third packaging method is by means of PCMCIA I/O card. PCMCIA release 2.0 has extended its card definition to include I/O modules. Many I/O modules, such as modems, LAN adapters, etc. have been built according to this standard. Compared with the external portable module, the PCMCIA I/O card can draw its power directly from the portable computer, and its functionality and performance is much better than a correspondent external portable module. Additionally, handling is also relatively easy since the cards are easily installed and removed and do not require external power converters and interfaces.
PCMCIA I/O cards have received generally good acceptance and many peripheral vendors are busy developing their own PCMCIA-standard I/O modules. Many portable computer vendors have included PCMCIA slot(s) in their new portable systems. However, there are still some serious weakness in PCMCIA's I/O card design.
First, it is difficult to increase the number of PCMCIA slots to achieve maximum modularity in a portable computer. A desktop computer usually has eight add-on card slots and four or five spaces for internally mounted disk drives, CD-ROMs, etc. A user can conveniently install many modules in a desktop computer which will generally reside inside the desktop computer for a long time once they are installed. 0n the contrary, a user must constantly change PCMCIA I/O modules for their portable computer because there is often only one or two PCMCIA slots offered in most portable computers. Increasing the number of PCMCIA slots in a portable computer is physically not a difficult task, but it results in a strange, inconvenient portable computer design. PCMCIA cards are designed for maximum portability, not for maximum modularity.
Secondly, I/O ports on PCMCIA I/O cards can only be placed on the card's rear end because the card is designed to be slid into a PCMCIA slot horizontally. Many chassis-dependent I/O ports, such as track-ball mice, speakers, control panels, etc., cannot be modularized based on the PCMCIA I/O card design. Modifications or changes of these chassis-dependent I/O ports lead to many hard tooling changes and PCB board relayout. The PCMCIA I/O card design offers no solution for it.
Thirdly, the PCMCIA I/O card design does not allow further modularization. Each PCMCIA I/O card must be built as an integral unit. Users cannot change its mechanical or electronic features for different electronic applications.
And finally, it is difficult, and often impossible, to use traditional PCB-based components and assembly technologies to build PCMCIA I/O cards. All the components must be shrunk into a very compact size and fit into a small, credit-card type enclosure. Material and assembly costs to produce PCMCIA I/O cards are very high.
In general, PCMCIA I/O cards and other packaging methods fail to serve as a standard packaging method to achieve a design for portable computers which delivers maximum internal modularity. New internal mounting mechanisms are necessary to increase the maximum number of internal I/O modules which a portable computer can accept, and to modularize those chassis-dependent I/O ports to allow easy reconfiguration by end users while also reducing the hard tooling changes and expense for portable computer vendors.